Acute Angle
An acute angle is an angle that measures greater than 0° and less than 90°.
Example 1
This scene in the the movie Harry Potter and the Sorcerer's Stone takes place at the end of the school term at Hogwarts when Dumbledore is announcing the winner of the House Cup. The acute angle is the tip of Dumbledore's chair.
"Now, as I understand it, the House Cup here needs awarding, and the points stand thus: In fourth place, Gryffindor, with three hundred and twelve points; in third, Hufflepuff, with three hundred and fifty-two; Ravenclaw has four hundred and twenty-six and Slytherin, four hundred and seventy-two." -Harry Potter and the Sorcerer's Stone, Page 305
Example 2
This scene in the the movie Harry Potter and the Order of the Phoenix takes place in the Ministry of Magic when Harry is going to his disciplinary hearing for performing magic outside of school. The elevator that Harry and Mr. Weasley are on at the moment has a sliding door with many diamonds on it, and the tips of the diamonds are all acute angles.
"The lift clattered into view and they hurried inside. Every time it stopped Mr. Weasley cursed furiously and pummelled the number nine button." -Harry Potter and the Order of the Phoenix, Page 134